JPH0456243B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a leveling instrument for measuring relative height for determining the height difference between two points.

[Conventional technology]

To measure specific height, a leveling rod and a leveling instrument are generally used. Set up a staff at the two measurement points,
These scales are read alternately with a leveling telescope placed horizontally, and the difference in readings is determined as the altitude difference.

In addition, a sighting crosshair is provided within the field of view of the leveling telescope, and two horizontal lines called stadia lines attached to this crosshair are used to calculate rough horizontal distances. Sometimes measurements are taken. In this case, the horizontal distance is calculated by reading the distance on the leveling rod between the stadia lines and using the telephoto magnification.

[Problem that the invention seeks to solve]

In conventional relative height measurement, the measurer has to read the scale of the leveling rod, which makes digital display difficult, and there is also the problem that it is impossible to read numerical values into a data processor, store data, or perform automatic data processing. Furthermore, the telescopic field of view of a leveling instrument is extremely narrow, at about 1°20', and the digits displayed on the leveling rod at coarser intervals than the scale may fall outside the field of view, leading to misreading of height values. The same is true for stadia surveying, which cannot be digitally read and displayed, making it difficult to automatically calculate and display horizontal distances.

In view of this problem, it is an object of the present invention to enable digital direct reading and display in specific height measurements using a leveling rod and a level.

[Means for solving the problem] The leveling instrument for measuring relative height of the present invention includes a leveling telescope,
an image sensor comprising a row of reading elements provided on the imaging side of the leveling telescope, a processing device for processing the image output of the image sensor, and a display for digitally displaying the output of the processing device; The processing device includes a decoding unit that decodes the code information into an altitude value based on the image output of a code pattern attached to the leveling rod at the survey point in correspondence with the altitude value, and a decoding unit that decodes the code information into an altitude value based on the image output, and the image sensor that decodes the code information into an altitude value based on the image output. a distance detecting section that measures the size of the upper code pattern image in correspondence with the number of the reading elements and calculates the approximate horizontal distance from the leveling instrument to the above-mentioned staff by inverse proportional calculation of the image size; The display device is characterized in that the altitude value and the approximate horizontal distance are displayed on the display.

[Effect]

An approximate value of the distance is determined by utilizing the fact that the size of the code pattern image on the image sensor expands or contracts depending on the horizontal distance between the level and the staff. Therefore, according to the above-mentioned configuration, the altitude value can be directly read digitally, and the approximate horizontal distance can be automatically measured and displayed without performing a troublesome stadia survey.

〔Example〕

FIG. 1 shows the optical system of a leveling instrument used in carrying out the present invention, and FIG. 2 shows the main part (front view) of the leveling rod to be measured.

On the graduation surface of the leveling rod 1, barcodes 2 for optical reading, in which altitude values from the base end are absolutely encoded, are arranged in the longitudinal direction (height direction) at a unit graduation interval P of, for example, 5 mm. Each barcode 2 is
It is composed of a narrow bar 2a (corresponding to logic "0"), a wide bar 2b (corresponding to logic "1"), and a space 2c. Elements 2a and 2b correspond to areas with low reflectance (black), and space 2c corresponds to areas with high reflectance (white). Code systems include 3of9 code, 2of5 code, and NRZ code (UPC/EAN/
JAN) etc. can be used.

The leveling instrument 3 has an optical system substantially the same as that of a known autolevel, and consists of an objective lens system 4, a parallel beam system 5, and an eyepiece system 6. The eyepiece system 5 includes a focusing lens 6a and a focusing mirror 6 with crosshairs and stadia lines.
b, an eyepiece lens 6c, etc. The parallel beam system 5 is an automatic leveling device that obtains a horizontal line of sight regardless of the inclination of the optical axis of the telescope.
b and a pendulum prism 5c suspended by a string.

A beam splitter 7 is inserted into the eyepiece lens system 6, and the split image light is focused on an image sensor 9 through a magnification lens system 8. This image sensor 9 may be, for example, a CCD line sensor, and is arranged in such a direction that the reading line coincides with the width direction of the leveling rod 1, that is, the direction in which the code elements of the barcode 2 are arranged. The output of the image sensor 9 is led to the processing circuit system shown in FIG. 3, where the read barcode 2 is decoded and the altitude value is displayed.

In FIG. 3, a barcode image of a leveling rod formed on an image sensor 9 through a magnification level system 8 is read as an electrical signal and sent to a comparator 11 via an amplifier 10. The comparator 11 clips the signal above a certain level E and extracts it as a barcode signal. At this time, if the image is not in focus or if the reading line is located in the line space 2d between barcodes 2 in Figure 2, the image output level is low and it is excluded without appearing in the comparator output. be done. That is, the decodable signal level is discriminated to minimize errors in decoded values.

The output of the comparator 11 is shaped by a waveform shaping circuit 12 and supplied to the CPU 13 as a code pulse that sets the bars 2a and 2b of the barcode 2 to a high level and the space 2c to a low level. CPU13 is
Based on the pulse width of the high level part of the code pulse, the narrow bar 2a is set to logic "0" and the wide bar 2 is set to logic "0".
b is distinguished as logic "1", and these are further decoded into altitude values.

The decoding algorithm in the CPU 13 can basically be a pulse width determination based on time measurement. In other words, the pulse width corresponding to the high level part of the input code pulse is made to correspond to the number of clock pulses to create time width data strings corresponding to narrow and wide element strings, and the magnitude comparison of each data can be made with a predetermined margin. and obtain the code bit string. The code bit string is converted into decimal by a decoder (decode table in the CPU program) for each digit, and is stored in memory as an altitude value.
It is displayed on the display 14. It is also possible to transfer the measured altitude value from the I/O port 15, for example of the RS232C type, to a data terminal such as a pocket computer.

Note that the decoding principle is the same even in the case of a so-called interleaved barcode system in which a narrow space and a wide space are provided in the space 2c of the barcode 2 and used as a code together with the bar element.

FIG. 4 is a front view of the rear panel of the leveling instrument 3, and displays 14 and 15 are provided above the eyepiece 6c, and the read altitude value is digitally displayed on the display 14. Note that the display 18 displays an approximate distance measurement value obtained by distance measurement, which will be described later.

As shown in the barcode format in FIG. 5, an identification symbol 21 ( ID code) can be added. This identification symbol 21 may be, for example, a special code that is difficult to produce naturally, such as a "0000" sequence (narrow bars and spaces appear alternately in groups of four).
The CPU 13 can be programmed to decode the main body of the barcode 2 when the identification symbol 21 can be read by the CPU 13. Alternatively, the identification symbols 21 may be provided at the front and rear ends of the main body of the barcode 2, and the decoding step may proceed only when the identification symbols 21 are correctly read at both ends.

After the identification symbol 21, for example, a four-digit data area 22 is provided, as shown in FIG.
A parity bit 23 is added to the tail. If necessary, a checksum 24 calculated according to the arithmetic defined in the coding system may be added.

Note that the identification symbol 21 may also be used as a start character and a stop character for causing the CPU 13 to recognize the reading start point and end point of code data. Also, the barcode 2 on the staff 1
It is preferable to add a start margin 25a and a stop margin 25b, which are non-signal portions of a certain width, before and after.

If the CPU 13 cannot correctly read the identification symbol 21 or the start/stop character code, the CPU 13 can issue an alarm signal and cause the display 14 to display an NG indication 14a. In this case, the operator looks through the eyepiece lens 6c and checks whether the check is in focus and whether the barcode 2 is correctly placed within the field of view.

Even if the reading line of the image sensor 9 is located in the line space 2d (no code part) of the longitudinal arrangement of the barcode 2 in FIG. 2, the barcode 2 (identification symbol 21) cannot be read. In this case, as shown in FIG. 3, the parallel glass 16 provided on the front side of the image sensor 9 is tilted by a small angle so that the optical axis is positioned so that the image of the barcode 2 is located on the reading line of the image sensor 9. Perform the operation of bending. By this operation, the identification symbol 21 can be read by shifting the image by a predetermined amount (1/2 pitch at most) in the longitudinal direction of the leveling rod.

If an actuator 17 for tilting the parallel glass 16 is further provided, the image forming position can be automatically corrected by activating this actuator 17 even with the above-mentioned alarm signal from the CPU 13 indicating a reading failure. I can do it. Even if the optical system is corrected to the equivalent of 1/2 pitch, if the interval between barcodes 2 is, for example, a unit scale interval of pitch p = 5 mm, the reading accuracy will deteriorate beyond the nominal measurement error of ±2.5 mm. There's nothing to do.

The actuator 17 can be composed of, for example, an eccentric wheel and a servo motor, and changes the angle of the optical axis continuously or discretely with a constant step width under the control of the CPU 13, and changes the imaging position on the image sensor 9. can be made to vary in the vertical direction. Furthermore, the optical axis may be moved laterally for visual field correction.

Note that if the image sensor 9 is equipped with a plurality of reading lines or a two-dimensional sensor with a matrix arrangement, when the barcode cannot be read in the line space 2d between the barcodes, the image sensor 9 can be shifted upward or downward with respect to the reading line. It can be configured so that it can be read using a separate reading line.

In order to improve reading accuracy and reduce reading errors, it is possible to adopt an uneven code arrangement as shown in FIG. 6. That is, barcode 2A with pitch p (unit scale interval) is provided as A series,
Barcode 2B with the same pitch p, adjacent to the width direction of the staff 1 and shifted by 1/2 pitch in the longitudinal direction
is set as the B series. According to this configuration, line space 2d (no code part) of barcode 2A
When the reading line of the image sensor 9 is located at the 2nd line and the identification symbol 21 cannot be read, the barcode 2B of the B series can be read successfully by switching to reading the barcode 2B.

If the code values of barcodes 1A and 2B are different by 1/2 pitch, the nominal measurement error can be halved (±1/4
It can be reduced to (Pitch). Also, even if the same code value is used for barcodes 2A and 2B,
If the CPU 13 recognizes the switching between the A series and the B series and performs a 1/2 pitch correction calculation on the decoded value, a highly accurate reading value with a nominal error of ±1/4 pitch can be obtained. It will be done. In order to switch the reading between the A series and the B series, the parallel glass plate 16 shown in FIG. . Furthermore, if the number of bits (number of elements) of the image sensor 9 used is sufficiently large and the resolution is sufficient, the area of the read line of the image sensor 9 can be divided into the first half and the second half.
and B-series barcodes 2A and 2B may be readable, respectively.

It is desirable that the barcodes 2A and 2B partially overlap in the longitudinal direction of the leveling rod 1. That is,
As shown in Fig. 6, if the bar length of the B-series barcode 2B is set to 1/2 pitch or more and overlaps the A-series barcode 2A in the longitudinal direction of the leveling rod 1, unreadability can be prevented. There will be no more occurrences.

Of course, as shown in the modification shown in FIG. 7, the bar lengths of both barcodes 2A and 2B may be made closer to the pitch p to increase the amount of overlap between them and improve the reading accuracy. However, in the case of FIG. 7, there are a wide range of height positions where both the A series and the B series can be read simultaneously, so the nominal accuracy is not substantially higher than the pitch p. In the case of FIG. 6, the nominal accuracy is improved because it is roughly equivalent to arranging barcodes every 1/2 pitch.

In the code arrangement of FIG. 6, identical barcodes 2A' and 2B' are added adjacent to barcodes 2A and 2B of series A and B, respectively. These barcodes 2A' and 2B' can be used for true value verification in the CPU 13. For example code 2A and 2
A verification algorithm can be incorporated to compare each bit with A' and perform decoding processing only when they match, and perform error processing when they do not match. Furthermore, when an error is found in the check bit or check code (parity, checksum, CRC, etc.) of one of the barcodes 2A or 2A', the other code may be read.

Add 3 more barcode steps as shown in Figure 8.
It may be increased by stages, 4 stages, and so on. In the case of three stages (2A to 2C) in FIG. 8, the nominal error is 1/3 of the pitch p of one series.

Next, FIG. 9 shows the relationship between the imaging plane, the barcode image, and the image signal output when a CC line sensor is used as the image sensor 9, and FIG. 10 shows the outline of the reading optical system.

The CCD line sensor has a row of light-receiving elements 30 at a position that coincides with the optical axis of the objective lens system 4, and if images of the narrow bar 2a and the wide bar 2b are formed on the imaging surface, the corresponding serial code pulses are generated. The signal S _p can be read out. According to the sampling theorem, if at least two light receiving elements 30 are included within the width of the image of the narrow bar 2a or the space 2c, the code can be read based on the pulse signal S _p .

In determining the resolution and number of bits (number of elements) of the CCD line sensor, it is necessary to consider the expansion and contraction of the image according to the change in the distance between the leveling rod 1 and the leveling gage 3. Regarding this point, it can be considered that the image on the imaging plane shrinks in approximately inverse proportion to the distance as described below. That is, when the reading optical system is composed of an objective lens system 4, a magnifying lens system 8, and an image sensor 9 as shown in FIG. If the distance to 2 is A and the distance to the imaging point is B, then 1/A+1/B=1/f, B=A・f/A−f, and the magnification u is u=B/A=B -f/f. In the case of a spirit level for measuring specific height, the distance A to the leveling rod is generally 2
The range is from m to 100m. Using objective lens system 4 with f=100mm, when A is 100m, B is approximately
At 0.1001 m, the magnification u is 0.001001 times. Therefore, when a barcode 2 with a width (total length of the barcode) of 20 mm is telescoped, the size of the image formed by the objective lens system 4 is approximately 0.02002 mm (20 μm).

Furthermore, when A is the shortest distance of 2 m, the image size is 1.05263 mm by similar calculation. That is, when the distance to the leveling rod 1 changes from 100 m to 2 m, the image size changes at a ratio of approximately 1:50.

Here, the number of modules of barcode 2 (the total of the entire barcode when narrow bar 2a is 1, wide bar 2b is 2 to 3, and space 2c is 1) is
50. The image sensor 9 requires resolution to obtain pulse signals corresponding to 50 modules.
To obtain the required resolution at distance A = 100m
The number of CCD elements is 100 bits, which is twice the total number of modules (50) considering the Nyquist spacing. Assuming that the spacing between the light receiving elements 30 of the CCD shown in FIG. 9 is approximately 10 μm, the size of the barcode image corresponding to 100 bits is required to be approximately 1 mm.
Therefore, if the magnification of the magnifying lens system 8 in FIG.
It is read in 100 bits, giving you the resolution you need.

When the distance A is 2 m, the image size is enlarged 50 times as described above, so the total number of CCD elements is required to be 5000 bits (100 bits x 50) or more (for example, 8192 bits). The size of the image on the imaging plane at this time is approximately 50 mm.

Note that by increasing the magnification of the telescope and increasing the total number of bits of the image sensor 9, it is possible to measure altitude differences at distances up to about 200 m. It is thought that reading the barcode becomes difficult beyond that due to the wavelength of the light and scintillation.

As mentioned above, by utilizing the fact that the size of the image on the light-receiving surface of the image sensor 9 is approximately inversely proportional to the distance, the approximate distance from the leveling instrument 3 to the staff 1 can be calculated.
It can be calculated and displayed by the CPU 13.
That is, the CPU 13 measures the width of the barcode image by clock counting based on the code pulse signal input from the waveform shaping circuit 12. In the above example, when the distance changes from 2m to 100m, the size of the image on the imaging plane changes from 50mm to 1mm, so the CPU 13 calculates the inverse proportion of the known constant from these relationships and the measured value of the image width. If this is done, an approximate distance measurement value can be obtained. This distance measurement value is displayed on the display 1 in Figures 3 and 4.
It will be displayed at 8.

Note that the reference distance (for example, 50
It is possible to calculate the imaging magnification at 2 m to 100 m with respect to This imaging magnification can be used as a normalization coefficient for each measurement pulse width in the narrow bar 2a and wide bar 2b discrimination algorithm during code reading. That is,
If the digital value of the pulse width corresponding to the narrow bar and wide bar is normalized in the CPU and then the discrimination algorithm of size comparison is executed, the program becomes simpler and the discrimination accuracy increases.

In the specific height measurement, a leveling rod is set up at two points and the difference between the respective altitude readings is used as the height difference, so this can be automated using the leveling instrument of the above-described embodiment. That is, barcode 2 of leveling rod 1
By reading the altitude values of each of the two points,
These differences can be stored in the CPU's memory and displayed as altitude differences.

Further, in the above-described embodiment, the surveyor looks into the eyepiece lens 6c of the leveling instrument to achieve the focused state, but since the focus differs depending on individual differences, an automatic focusing method may be used. For example, a focusing lens motor and its servo circuit can be added that performs servo operation so that the differential level of the image output of the image sensor 9 is maximized.

Furthermore, although the leveling instrument 3 of the above-described embodiment is a so-called auto-leveling device equipped with an automatic leveling correction system, it can also be applied to a manual leveling type Y level or tailing level using a bubble tube.

Further, in the embodiment, a bar code is used as the altitude scale, but a coding system using a square segment may also be used. Alternatively, the altitude numbers and altitude scale for each digit attached to a normal leveling rod may be used in combination.

〔Effect of the invention〕

According to the present invention, by reading the altitude value code pattern attached to the leveling rod, the altitude value can be directly read digitally, and the approximate horizontal distance from the leveling rod to the leveling rod can be measured based on the size of the code pattern image on the image sensor. Since the structure is configured to digitally display the data, there is no need to carry out troublesome stadia surveying during specific height surveying, and surveying work can be carried out efficiently and easily.

Furthermore, since an image sensor for altitude reading is used as the horizontal distance detection means, there is no need to provide a dedicated detection element for horizontal distance detection, and a highly functional digital leveling instrument can be obtained with a simple configuration.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram of the optical system of the leveling instrument according to the present invention, Fig. 2 is an enlarged view of the main parts of the leveling rod, Fig. 3 is a block diagram of the data processing circuit, Fig. 4 is a rear front view of the leveling instrument, and Fig. 5 is a format diagram of a barcode attached to a leveling rod, Figures 6 to 8 are schematic diagrams showing modified examples of barcode arrangement, and Figure 9 is a diagram showing barcode imaging and image output on an image sensor (CCD). The schematic diagram shown in FIG. 10 is a schematic diagram of the reading optical system. In addition, in the symbols used in the drawings, 1... leveling rod,
2...Barcode, 3...Level, 4...Objective lens system, 5...Parallel beam system, 6...Eyepiece system, 7...Beam splitter, 8...Magnification lens system, 9...Image It is a sensor.

Claims (1)

[Scope of Claims] 1. A leveling telescope, an image sensor comprising a row of reading elements provided on the imaging side of the leveling telescope, a processing device for processing the image output of the image sensor, and an output of the processing device and a display for digitally displaying the information, and the processing device includes a decoding unit that decodes the code information into an altitude value based on the image output of the code pattern attached on the staff at the survey point in correspondence with the altitude value. Based on the image output, the size of the code pattern image on the image sensor is measured in correspondence with the number of reading elements, and the approximate horizontal distance from the leveling instrument to the leveling rod is calculated in inverse proportion to the image size. and a distance detecting section for calculating a specific height, wherein the leveling instrument for measuring relative height is characterized in that the display device displays the altitude value and the approximate horizontal distance.